Devices and Methods for Continuous BioDiesel Production

ABSTRACT

At least one exemplary embodiment is directed to a device that combines feedstock oil and methoxide mix MM (methoxide and/or additional mixing components) along micro channels into a micro mixing channel/chamber, wherein the flow mix and continuously flow.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of No. 60/745,659, under 35 U.S.C. § 119(e), filed 26 Apr. 2006, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates in general to devices and methods of for the automation of biodiesel production and in particular, though not exclusively, for the continuous production of biodiesel.

BACKGROUND OF THE INVENTION

Biodiesel production is traditionally a batch process taking many hours to produce the final product.

The current method of biodiesel production involves picking up a feedstock oil (e.g. soybean oil, waste oil) delivering the feedstock oil to a storage facility, then to processing plant, then to a biodiesel storage tank, then shipping the finished product (e.g., biodiesel) back to the regional areas to serve as fuel. A business method that would locally process collected feedstock oil would significantly decrease transportation costs involved with biodiesel production and improve the overall efficiency of the market delivery.

The process of a biodiesel production facility in general is as follows: The feedstock oil storage pumps feedstock oil into the processing plant; a sample of the feedstock oil is used in titration to determine the useful catalyst levels; the useful level of catalyst is added to methanol to form methoxide, which is mixed with the feedstock oil in a batch mixing device; the products from the mixing device includes a mixture which includes glycerin, unused feedstock oil, and biodiesel; the unused portion of feedstock oil can be separated in a separating device and recycled in a recycling loop and injected back into the mixing device; the gycerine/waste can also be separated via the separating device and stored for later use; and finally the separated biodiesel (which can also be water washed) can be pumped into a biodiesel storage tank.

SUMMARY OF THE INVENTION

At least one exemplary embodiment is directed to an aphronated biodiesel production system, where the aphrons formed include a portion of feedstock oil and a portion of methoxide, which mix to produce biodiesel and glycerin.

At least one further exemplary embodiment is directed to a continuous biodiesel production device which includes at least two channels (e.g., in one exemplary embodiment the channels are micro channels where any channel has at least one dimension<1000 micrometers), a first and a second channel, where the first channel is configured to carry feedstock oil (FO), and the second channel is configured to carry methoxide (MO), where the first and second channels further intersect with a third channel or chamber, where the FO and MO flows mix and continue to flow.

Further areas of applicability of exemplary embodiments of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limited the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the drawings in which:

FIG. 1 illustrates the relationship between the volumetric flow rate f, the exit area Ae and the flow stream length Le in a given time;

FIG. 2 illustrates the relationships between the volumetric flow rates fa, fab, with the respective exit areas A_(A) and A_(B), and the respective flow lengths L_(A) and L_(B);

FIG. 2A illustrates how various properties (e.g., exit area, flow rates) can result in a non reactive interface, effecting mixing efficiency;

FIG. 3 illustrates a co-axial aphron (a droplet with a yoke and a sheath) generator, where the property relationships (flow rates 360, 370, and exit areas A_(I) and A_(O)) can be designed to maximize aphron formation and/or mixing efficiency;

FIG. 4 illustrates the relationship between the inner flow rate fi, the outer flow rate fo, the inner exit area A_(I) and the outer exit area A_(o), such that the relative velocities vo and vi can be matched;

FIG. 5 illustrates a mixing device that includes flowing a first flow (e.g., feedstock oil for example vegetable oil, soybean oil, algae produced oil, and other oils that can be used to generate the product (e.g., biodiesel)) through a first section (e.g., of a channel, slot, chamber, pool, or other carrying or conveying elements or device as known by one of ordinary skill in the relevant arts), and a second flow into a mixing chamber forming a mixing flow, where the mixing flow can impinge upon mixing grids (for example that can decrease in size along the mixing length (flow direction));

FIG. 6 illustrates a micro mixing device that can be molded or etched, mixing microfluidic flows, where the smaller sizes increases the effective surface area of interaction and mixing (Note that herein in this specification a device designed for micro systems can be scaled to macro systems within the scope of exemplary embodiments);

FIG. 7A illustrates a top view of another exemplary embodiment of a micro mixer having multiple microfluidic flows mixing into a mixing flow that can optionally impinge on a filter (e.g., micropore) separating portions of the product from the mixing flow;

FIG. 7B illustrates yet a further exemplary embodiment of a micro mixer wherein outer flows of a mixture that can be used to form biodiesel from feedstock oil (e.g., methoxide mixture MM) are mixed with an inner flow of feedstock oil; and

FIG. 8 illustrates a aphronator mixing device, wherein a first and second flow form aphrons, where the yoke and sheath mix forming a product, where the two flows are inserted into an aphron generator which can be optionally shaked to form uniform aphrons.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

The following description of exemplary embodiment(s) is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Processes, methods, materials and devices known by one of ordinary skill in the relevant arts may not be discussed in detail but are intended to be part of the enabling discussion where appropriate.

Additionally, the size of structures formed using the methods and devices of exemplary embodiments are not limited by any discussion herein (e.g., the sizes of structures can be macro (centimeter, meter, size), micro (micro meter), nanometer size and smaller).

Additionally, examples of mixing/separating/sampling device(s) are discussed, however exemplary embodiments are not limited to any particular device for mixing, separating, and sampling.

Additionally, other fluid besides those used in biodiesel production can be used with the exemplary embodiments including gases.

FIG. 1 illustrates the relationship between the volumetric flow rate f, the exit area Ae and the flow (stream) length Le in a given time. FIG. 1 illustrates a channel flow 100, where the fluid has a flow rate 105 (f) and flows along a section of a channel 114. The flow rate can be controlled by a fine control valve 110. The channel has an exit area Ae (120). The relationship between the flow length Le, the flow rate f, the exit area Ae in a given time t is given by:

Le=(ft)/Ae   (1)

FIG. 2 illustrates the relationships between the volumetric flow rates fa, fab, with the respective exit areas A_(A) and A_(B), and the respective flow lengths L_(A) and L_(B). Ideally one would like to maximize the interaction surface, thus match L_(A) and L_(B), which also can be accomplished by matching flow velocities such that the relative velocity between flow 230 a and 230 b is near zero. To match the flow velocities one can set L_(A)=L_(B) and use equation 1 to derive a relationship between the flow rates (fa, fb) and the exit areas (A_(A) and A_(B)), which can be expressed as:

(A_(A)/A_(B))≈(fa/fb)   (2)

FIG. 2A illustrates how various properties (e.g., exit area, flow rates) can result in a non reactive interface, effecting mixing efficiency. When the flow velocities are not nearly matched there is a non reactive interface.

FIG. 3 illustrates a co-axial aphron (a droplet with a yoke and a sheath) generator 300, where the property relationships (flow rates 360, 370, and exit areas A_(I) and A_(O)) can be designed to maximize aphron formation and/or mixing efficiency. An outer channel 305 can have within (about co-axially) and inner channel 307. The outer channel can carry an outer flow 320 and the inner channel an inner flow 310, where the inner flow has a flow rate 370 and the outer flow has a flow rate of 360. FIG. 3 illustrates the inner channel exit area Ai and the outer channel exit area Ao 340 as separate form the channels for clarity. As in FIG. 2 the properties of the inner and outer flows can be matched to match flow lengths Li and Lo (or alternatively the flow velocities of the inner and outer such that the relative flow velocity is near zero). For example if we choose the outer volumetric flow rate to be 0.2 of the total (outer+inner volumetric flow rates), then matching Lo and Li, and choosing the dimensions of the inner channel (e.g., inner hole radius r0, outer edge of inner channel radius r1) one can obtain a relationship for the geometry of the outer channel (e.g., inside radius of outer channel r2), which can be expressed as:

r2=sqrt(0.25(r0)̂2+(r1)̂2)   (3)

FIG. 4 illustrates the relationship between the inner flow rate fi, the outer flow rate fo, the inner exit area A_(I) and the outer exit area A_(O), such that the relative velocities vo and vi can be matched to maximize uniform aphron formation. If the inner and outer flows are matched and instabilities are produced (e.g., shaking the tubes along the flow path at a choosen frequency) uniform aphrons can be produced. The size of the aphrons will depend upon the properties of the two flows (as discussed) and the frequency. Hence a frequency of 100 Hz will generally result in 100 droplets per second. Thus from the flow properties and the frequency the volume of the yoke 410 and sheath 420 can be calculated. Various size aphrons can be produced to determine the size of the ratio of sheath to yoke volumes and size that maximize the mixing of the yoke and sheath (e.g., maximize complete mixing by computing the amount of sheath needed to convert the yoke into biodiesel, e.g., ratio of sheath volume to yoke approximately 10-30%).

FIG. 5 illustrates a mixing device that includes flowing a first flow (e.g., feedstock oil for example vegetable oil, soybean oil, algae produced oil, and other oils that can be used to generate the product (e.g., biodiesel)) through a first section (e.g., of a channel, slot, chamber, pool, or other carrying or conveying elements or device as known by one of ordinary skill in the relevant arts), and a second flow into a mixing chamber forming a mixing flow, where the mixing flow can impinge upon mixing grids (for example that can decrease in size along the mixing length (flow direction)). The mixing device 500 has at least two chambers 550, and 560, that hold and direct a first flow (e.g., feedstock oil, FO) through a first channel 520, that passes, in this non-limiting example, through the reservoir for the second fluid (e.g., methoxide and/or other mixtures MM), which flows through a second channel 530. The first and second flows are injected into a mixing section, forming a mixing flow, where the flow velocities can be matched to produce enhanced mixing (for example if the relative volume ratios are chosen), or the relative velocities can be varied for different flow properties by taking advantage of additional material (FIG. 2A) to obtain the desired volume ratio in the mixing section. Note that although channels are shown, slots or other types of configurations for delivering the flows can be used within the scope of at least one exemplary embodiment.

FIG. 6 illustrates a micro mixing device that can be molded or etched, mixing microfluidic flows, where the smaller sizes increases the effective surface area of interaction and mixing (Note that herein in this specification a device designed for micro systems can be scaled to macro systems within the scope of exemplary embodiments). The micro mixer 600, can include a bottom etched/molded or otherwise formed substrate 620, that can be covered by another substrate 610. Two microflows 640 and 630 can be directed into a mixing section 650, where the two flows mix. The dimensions of the chambers, flow rates (e.g., governed by suction pressures at either end of a micro channel) can be determined by principles already discussed. Note that a micro mixing device increases the effective surface of interaction, thus a micro mixing device with a multiple of micro channels having the same effective flow rates as two channel macro system, will have a larger interaction surface (interface surface between both flows), and thus will have an increased mixing efficiency when compared to and equivalent macro system.

FIG. 7A illustrates a top view of another exemplary embodiment of a micro mixer having multiple microfluidic flows mixing into a mixing flow that can optionally impinge on a filter (e.g., micropore) separating portions of the product from the mixing flow. The mixing device 700 in FIG. 7A illustrates a micro mixing device with multiple channels (710 a-e).

FIG. 7B illustrates yet a further exemplary embodiment of a micro mixer wherein outer flows of a mixture that can be used to form biodiesel from feedstock oil (e.g., methoxide mixture MM) are mixed with an inner flow of feedstock oil. FIG. 7B illustrates how various geometrical various in the geometry (e.g., curved channels, piezoelectric mixing via oscillating walls) can be used to enhance mixing.

FIG. 8 illustrates a aphronator mixing device 800, wherein a first 840 a and second 840 b flow form aphrons, where the yoke and sheath mix forming a product, where the two flows are inserted into an aphron generator 840 which can be optionally shaked (e.g., via a linear oscillator 815 connected to a function generator 810, the linear oscillator operatively connected 830 a to a movable plate 850 containing the aphron generator 840, which then shakes) to form uniform aphrons. The resultant aphrons can accumulate in a chamber where mixing continues, or can be impinged upon various grids or objects to break up the aphrons to improve mixing.

Note that when discussing matching flow velocities, one can also use flow velocity mismatch to obtain the desired volume ration for optimum mixing. When matching flow velocities to a threshold then, the threshold is chosen so that either the relative flow velocity is low (e.g., <10% of the slowest flow, or near zero) or with the geometry and properties of the channels already set, then the threshold is chosen so that the relative flow rates are mismatched so that in a given amount of time the optimum volumetric ration is obtained in the mixing section. For example if the channels where identical, the volumetric flow rates can be chosen so that one flow (e.g., methoxide flow) delivers a volume in a time t that is 10-30% the volume delivered by the second flow (e.g., feedstock oil) enhancing the opportunity of complete mixing. Additionally the threshold can be chosen to maximize mixing, for example by maximizing the % of product in the mixed flow along a given length of the mixing section.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 

1. A method of continuous product generation comprising: generating a first flow of a first mixture along a first section, having a first volumetric flow rate; generating a second flow of a second mixture along a second section, having a second volumetric flow rate, wherein a geometry of the first and second sections are such that the first flow and the second flow have a relative velocity equal to or below a threshold value; and mixing the first flow and the second flow along a third section to form a mixing flow, where the threshold value is selected to maximize mixing of the first and second flow along the third section.
 2. The method of claim 1, wherein the first flow and the second flow are substantially co-axial, and wherein the first flow is surrounded by the second flow.
 3. The method of claim 1, wherein the threshold value is selected to maximize the percentage of mixing product that results from mixing the first and second flow that occurs along the shortest distance along the third section.
 4. The method of claim 1, wherein the threshold value is about zero.
 5. The method according to claim 1, wherein at least one dimension of at least one of the first, second, and third sections is less than 1000 microns.
 6. The method according to claim 2, wherein the first flow includes feedstock oil.
 7. The method according to claim 6, wherein the second flow includes a mixture to convert the feedstock oil into biodiesel.
 8. The method according to claim 7, wherein the mixture includes a catalyst and an alcohol.
 9. The method according to claim 7, wherein the mixture includes methoxide.
 10. The method according to claim 7, wherein the mixing step includes breaking the first and second flow into aphrons, wherein the sheath and yoke mix in time to form at least a portion of biodiesel.
 11. The method according to claim 5, wherein the first flow includes feedstock oil, wherein the second flow includes a mixture to convert the feedstock oil into biodiesel, and wherein the mixing flow includes biodiesel and feedstock oil, further comprising: separating at least a portion of biodiesel from feedstock oil by impinging the mixing flow upon a micropore filter, wherein the micropore filter is any filter that allows one of either the biodiesel or feedstock molecule to pass through. 